The flight from San Francisco to Phoenix took 18 hours and 18 minutes — and didn’t use a drop of
fuel.

A solar-powered airplane that developers hope eventually to pilot around the world landed safely
in Phoenix yesterday on the first leg of an attempt to fly across the United States using only the
sun’s energy, project organizers said.

The plane, dubbed the Solar Impulse, completed the first of five legs; ahead in the coming weeks
are planned stops in Dallas, St. Louis and Washington on the way to a final stop in New York.

The spindly plane barely hummed as it took off on Friday from Moffett Federal Airfield, a joint
civil-military airport near San Francisco.

It landed in predawn darkness at Sky Harbor International Airport in Phoenix, according to a
statement on the Solar Impulse’s website.

The flight crew plans pauses at each stop to wait for favorable weather. It hopes to reach John
F. Kennedy International Airport in New York in about two months.

The Swiss pilots and co-founders of the project, Bertrand Piccard and Andre Borschberg, will
take turns flying the plane, which has a single-seat cockpit. Piccard was at the controls for the
flight to Arizona.

The lightweight carbon-fiber Solar Impulse has the wingspan of a jumbo jet and the weight of a
small car.

The plane was designed for flights of up to

24 hours and is a test model for a more-advanced aircraft the team plans to build to
circumnavigate the globe in 2015. It made its first intercontinental flight, from Spain to

Morocco, in June.

The aircraft is propelled by energy collected from 12,000 solar cells built into the wings that
simultaneously recharge four large batteries with a storage-capacity equivalent to a Tesla electric
car. The batteries allow it to fly after dark.

The lightweight design and wingspan allow the plane to save energy but also make it vulnerable.
It cannot fly in strong wind, fog, rain or clouds.